The electric machine is in particular a rotating electric machine such as a synchronous generator to be connected to a gas or steam turbine (turbogenerator) or a synchronous generator to be connected to a hydro turbine (hydro generator) or an asynchronous generator or a synchronous or asynchronous electric motor or also other types of electric machines. The basic structure of such an electric machine is a stator with a stator core enclosing a rotor with rotor core in operation. The stator core is composed from laminated annular sheets which are stacked on each other to form a cylinder. The stacking of the stator core can be done with a horizontally directed stack or with a vertically directed stack. In this disclosure the horizontal stacking is described. In maintenance and repair procedures sometimes parts of the stator core are replaced instead of the complete stator core. These parts are single sheets or stacks of several sheets. Different methods exist to achieve the stacking which has to fulfil high requirements in terms of precision to arrange the heavy parts. Mostly, devices are installed inside the stator core to stack sheets on the stator core. These devices comprise rails inside the stator housing or stator frame on which dollies carrying the sheets are moved. It is especially useful, in the context of duration of the stack procedure including the organization and built up of the necessary structure, to provide a different solution. The state of the art merely provides for stackers and methods to stack a stator core which require a substantial amount of time with corresponding costs involved.